Multivariate Regression Equation Research Articles

Pay dissatisfaction and withdrawal behaviour of employees in the civil service: does personal income tax regime matter?

PurposeThe aim of the study is to explore the links between multiple personal income tax regimes, pay dissatisfaction, employee lateness and absenteeism. Accordingly, this paper examines the relationships between income tax policies, pay dissatisfaction and the work withdrawal behaviours of employees in the public service.Design/methodology/approachThe study adopted a quantitative design, and data were collected through a structured questionnaire from a sample of 252 respondents from the Bayelsa State Civil Service in Nigeria. Data were analysed by applying multivariate regression and structural equation modelling through the use of Stata software version 12 and SmartPLS version 4.FindingsThe results demonstrated that there was a positive relationship between personal income tax regimes and pay dissatisfaction; there was a positive relationship between pay dissatisfaction and work withdrawal behaviour of employee tardiness and absenteeism and pay dissatisfaction mediated the relationships between personal income tax regimes and work withdrawal behaviours of public sector employees.Originality/valueThe study appears to be the first to explore the nexus between personal income tax regimes and pay dissatisfaction and withdrawal behaviours of employee tardiness and absenteeism as well as the mediating role of pay dissatisfaction in public service organisations.

Multi-Objective Optimization of Process Parameters in Laser DED Ni-Based Powder on Steel Rail Using Response Surface Design

With the rise of global industrialization, the requirements for the operating speed and carrying capacity of high-speed trains are increasingly higher. Because the wear and tear of rails gradually increases during the running of high-speed trains, strengthening or repairing rail surfaces is of paramount significance. Laser-directed energy deposition (DED) exhibits significant advantages in improving surface hardness, corrosion resistance, and abrasion resistance. Because of the multiple interacting optimization objectives, the development of a multi-objective optimization method for process parameters is significant for improving DED deposition quality. Response surface design employs multivariate quadratic regression equations to fit the functional relationship between the factors and the responses, which can be employed to find the optimal process parameters and solve multivariate problems. This study develops a multi-objective optimization model with response surface design and 2D process mappings to visually analyze the effects of scanning speed, laser power, and powder feed rate on aspect ratio, dilution rate, and microhardness. The optimal combination of process parameters for Ni-based alloys on U71Mn rail is a laser power of 431 W, a scanning speed of 5.34 mm/s, and a powder feed rate of 1.03 r/min. In addition, a multi-physics field finite element model is developed to analyze the evolution mechanism of the microstructure from the bottom to the top of the single track. This study can provide theoretical and technical support for the surface strengthening or repair of U71Mn rail.

Colorectal cancer information avoidance is associated with screening adherence.

Colorectal cancer (CRC) is the fourth most common cancer among U.S. men and women and the second deadliest. Effective screening modalities can either prevent CRC or find it earlier, but fewer than two thirds of U.S. adults are adherent to CRC screening guidelines. We tested whether people who defensively avoid CRC information have lower adherence to CRC screening recommendations and weaker intentions for being screened and whether CRC information avoidance adds predictive ability beyond known determinants of screening. Participants, aged 45-75 years, completed a survey about known structural determinants of CRC screening (healthcare coverage, healthcare use, provider recommendation), CRC information avoidance tendencies, and screening behavior (n = 887) and intentions (n = 425). Models were tested with multivariable regression and structural equation modeling (SEM). To the extent that participants avoided CRC information, they had lower odds of being adherent to CRC screening guidelines (OR = 0.55) and if non-adherent, less likely to intend to be screened (b=-0.50). In the SEM model, avoidance was negatively associated with each known structural determinant of screening and with lower screening adherence (ps < 0.01). Fit was significantly worse for nested SEM models when avoidance was not included, (i.e., the paths to avoidance were fixed to zero). Information avoidance was associated with screening behavior and other known structural determinants of screening adherence, potentially compounding its influence. Novel strategies are needed to reach avoiders, including health communication messaging that disrupts avoidance and interventions external to the healthcare system, with which avoiders are less engaged.

Foreign direct investment and domestic innovation: Roles of absorptive capacity, quality of regulations and property rights.

Foreign Direct Investment is theoretically expected to facilitate the transfer of knowledge from the home country to the host country, however, the empirical evidence on the subject is mixed. Some studies have shown that, on one hand, as competition grows, the incentive to innovate reduces with the decrease in monopoly rents (Schumpeterian effect). On the other hand, market competition can also boost investments in R&D activities incentivized by incremental profits (Escape-Competition effect). Therefore, this study aims to explore which of these two effects dominates in the selected group of countries. This study also identifies the moderators of the relationship between FDI stock and domestic innovation. It examines the role of absorptive capacity, quality of regulations, and property rights protection in the innovative activities of the host countries. Generalized Method of Moments is used to estimate the parameters of the multivariate regression equation. The analysis is based on panel data consisting of 49 countries over 14 years. The results show that FDI has a negative relationship with domestic innovation, indicating the presence of the Schumpeterian effect. The extensions of the main models show that FDI positively affects domestic innovation in countries with higher absorptive capacity, the superior quality of regulation, and stronger protection of property rights. This study shows that the positive relationship between FDI and domestic innovation is conditional on the ability to absorb knowledge and quality of governance in the recipient countries.

The relationships between optimal infant feeding practices and child development and attained height at age 2 years and 6-7 years.

Limited evidence exists on the long-term effects of early feeding practices on child growth and development. We examined the relationships between infant feeding practices and child height and development at ages 2 and 6-7 years. We studied 885 mother-child dyads from a randomized controlled trial of preconception supplementation in Vietnam. Early initiation of breastfeeding (EIBF), exclusive breastfeeding (EBF), breastfeeding (BF) duration and minimum dietary diversity (MDD) were assessed using World Health Organization(WHO) guidelines. Child development was assessed by the Bayley Scales of Infant Development-III at 2 years and the Wechsler Intelligence Scale for Children®-IV at 6-7years. Child height-for-age z-score (HAZ) was calculated from child height and age. Multivariable regression and structural equation models were used in analyses that controlled for confounding. EIBF and EBF at 6monthsoccurred in 52% and 62% of children, respectively. Mean breastfeeding duration was 18 monthsand 83% achieved MDD at 1year. EIBF was associated with motor (β = 0.13, 95% confidence interval [CI]: 0.00, 0.28) and cognitive development at 2years(β = 0.12, 95%CI: -0.01, 0.26), which in turn were positively associated with cognitive development at 6-7years. EBF was directly associated with development at 6-7years (β = 0.21, 95% CI:0.08, 0.34) whereas motor and cognitive development at 2years explained 41%-75% of the relationship between EIBF and development at 6-7years. HAZ at 2years also mediated 70% of the association between MDD at 1year and HAZ at 6-7years. BF duration was not associated with child development and HAZ. Early infant feeding practices, especially EIBF and EBF, have important long-term implications for optimizing child linear growth and cognition as they begin school.

Inter-well Connectivity Mapping System Based on Production Dynamic Data

In the process of oilfield development, interwell connectivity is an important index for reservoir evaluation, but after most of the oilfields enter into the medium-high water content development stage, the evaluation of interwell connectivity becomes the key to improve the efficiency of injection and recovery development. In order to solve the problems of time-consuming and costly of the traditional dynamic connectivity research methods, a water-driven injection and recovery inter-well connectivity calculation model was established through the study of Liu76-60 well group. In the process of the study, the inter-well model was established by processing the data of the well group, and the inter-well connectivity between injection and extraction wells was calculated on the basis of this model, and the calculated results were verified by multivariate linear regression equations. The final results show that the model established in the study is more accurate in evaluating the inter-well connectivity, and the comparison can be confirmed to be consistent with the results of the production dynamics, so the model can be used to evaluate the inter-well connectivity, which has a positive effect on the effective improvement of the efficiency of injection and recovery development in the reservoir.

Crystal chemistry and molar volume of potassic-chloro-hastingsite

Abstract. Several geological processes such as crustal and mantle metasomatism, high-grade metamorphism, and the formation of ore deposits involve the exchange of halogens, especially chlorine, between silicate minerals and fluids. It is well established that the presence of octahedral iron is vital to the process of Cl incorporation into amphiboles. However, other compositional controls on Cl incorporation, such as the effect of TAl, ANa, AK, and A-site occupancy are not as well constrained. This study reports on the compositional and structural relationships amongst a suite of 25 synthetic calcium amphiboles with a diverse range of Cl contents (0–1.68 atoms per formula unit (apfu)). Most amphiboles were synthesized along the potassic-hastingsite–potassic-chloro-hastingsite join (KCa2(Fe4Fe3+)(Al2Si6)O22(OH,Cl)2). Additional work involved substitution of Na for K, variable Al content, and substitution of Mg for Fe2+ in the bulk composition to explore these compositional effects on Cl incorporation. The relationship between pressure and the Cl content of amphiboles was also explored over the pressure range 0.3–2.0 GPa. Otherwise, synthesis conditions were 700 °C and 0.3 GPa with fO2 near Ni–NiO. Iron (II) chloride was used as the source of Cl. Some experiments used variably concentrated FeCl2 brines (0–100 molal), while others were nominally anhydrous, containing only the water absorbed by the hygroscopic FeCl2. All amphiboles were characterized by Rietveld refinements of powder X-ray diffraction patterns, electron microprobe analysis, and Mössbauer spectroscopy, the latter to determine Fe3+ fraction. This study finds a positive relationship between pressure and the Cl content of the amphibole. Both Fe2+ and Fe3+ are positively correlated with Cl among amphiboles with variable Fe#, but the correlation is poor to nonexistent for Mg-free amphiboles. Results indicate that the substitution of CFe2+,3+ for CMg and CFe2+,3+ for CAl facilitate Cl incorporation, with the former having a larger effect. The A-site occupancy is positively correlated with Cl in all amphiboles except those synthesized in dilute FeCl2 brines (≤ 6 m), which are negatively correlated. No correlation is observed between the Cl content of the amphibole and either the species of A cation (K vs. Na) or TAl. The composition vs. unit cell parameter data were analyzed using multivariate linear regression to better understand the process of Cl incorporation and to predict the molar volume of endmember chloro-amphiboles. The regression indicates an expansion of 0.181 Å (0.99 %) and 0.048 Å (0.90 %) along the b and c edges respectively, a reduction in β by 0.76° (0.72 %), and a contraction of 0.060 Å (0.59 %) along a when fully substituting Cl for OH in potassic-hastingsite. The multivariate linear regression equations allow the prediction of molar volumes for select endmember chloro-amphiboles, such as potassic-chloro-hastingsite = 964.63 ± 1.29 Å3 or 290.5 ± 0.4 cm3 mol−1.

Early-life cumulative exposure to excess bodyweight and midlife cognitive function: longitudinal analysis in three British birth cohorts

Excess bodyweight (BMI >25 kg/m2) in midlife (age 40-65 years) has been linked to future cognitive decline and an increased risk of dementia. Whether chronic exposure to excess bodyweight in the early decades of life (<40 years) is associated with compromised cognitive function by midlife, however, remains unclear. This study therefore aimed to test potential bidirectional direct and indirect pathways linking cumulative exposure to excess bodyweight and cognitive function in the early decades of life. In this longitudinal analysis, harmonised measures of BMI and cognitive function were available in 19 742 participants aged 47-53 years recruited to the 1946 National Survey of Health and Development (n=2131), the 1958 National Child Development Study (n=9385), and the 1970 British Cohort Study (n=8226). Individual BMI trajectories spanning three decades from age 10-40 years were created for each participant and excess bodyweight duration, BMI change between ages, and cumulative excess bodyweight exposure were calculated. Harmonised measures of verbal and non-verbal ability, mathematical ability, and reading ability were used to create a latent factor for childhood cognitive function, and immediate and delayed recall, animal naming, and letter-search speed tests were used for midlife cognitive function. Multivariable linear regression and structural equation models (SEM) were used to test for potential bidirectional relationships between cognition and excess bodyweight in both individual cohorts and pooled datasets while accounting for other potential early-life confounders. Increases in BMI during adolescence and greater cumulative exposure to excess bodyweight across early life were associated with lower midlife cognitive function in all cohorts (eg, pooled difference in cognitive function per 10 years excess bodyweight duration -0·10; 95% CI -0·12 to -0·08; p<0·001). Further adjustment for childhood cognitive function attenuated many of these associations towards the null (eg, pooled difference in cognitive function per 10 years excess bodyweight duration -0·04; 95% CI -0·06 to -0·02; p=0·001), however, with any remaining associations then fully attenuating once further adjusted for other early-life factors (eg, pooled difference in cognitive function per 10 years excess bodyweight duration 0, -0·03 to 0·01; p=0·38). In the reverse direction, low childhood cognition was associated with greater cumulative exposure to excess bodyweight over the next four decades, although much of this relationship was found to probably be explained via other potentially modifiable upstream early-life factors such as childhood disadvantage. SEM in all cohorts suggested the presence of modest direct and indirect pathways connecting earlier cognitive function to later excess bodyweight, but scarce evidence for an effect of early-life excess bodyweight on cognitive function by midlife. The association between cumulative exposure to excess bodyweight in early life and lower cognitive function in midlife is probably confounded by a persistently lower cognitive function from childhood. Initiatives to improve early-life factors such as childhood disadvantage and education, however, might exert dual but independent benefits on both of these factors before old age. Alzheimer's Research UK, Diabetes Research and Wellness Foundation, Diabetes UK, British Heart Foundation, and Medical Research Council.

First mobilisation after abdominal and cardiothoracic surgery: when is it actually performed? A national, multicentre, cross-sectional study

ObjectivesKnowledge of clinical practice regarding mobilisation after surgery is lacking. This study therefore aimed to reveal current mobilisation routines after abdominal and cardiothoracic surgery and to identify factors associated with...

The role of constraints and information gaps in driving risky medicine purchasing practices in four African countries.

Substandard and falsified (SF) medical products pose a major threat to public health and socioeconomic development, particularly in low- and middle-income countries. In response, public education campaigns have been developed to alert consumers about the risks of SF medicines and provide guidance on 'safer' practices, along with other demand- and supply-side measures. However, little is currently known about the potential effectiveness of such campaigns while structural constraints to accessing quality-assured medicines persist. This paper analyses survey data on medicine purchasing practices, information and constraints from four African countries (Ghana, Nigeria, Sierra Leone and Uganda; n > 1000 per country). Using multivariate regression and structural equation modelling, we present what we believe to be the first attempt to tease apart, statistically, the effects of an information gap vs structural constraints in driving potential public exposure to SF medicines. The analysis confirms that less privileged groups (including, variously, those in rural settlements, with low levels of formal education, not in paid employment, often women and households with a disability or long-term sickness) are disproportionately potentially exposed to SF medicines; these same demographic groups also tend to have lower levels of awareness and experience greater levels of constraint. Despite the constraints, our models suggest that public health education may have an important role to play in modifying some (but not all) risky practices. Appropriately targeted public messaging can thus be a useful part of the toolbox in the fight against SF medicines, but it can only work effectively in combination with wider-reaching reforms to address higher-level vulnerabilities in pharmaceutical supply chains in Africa and expand access to quality-assured public-sector health services.

Study on serum uric acid concentration and serum uric acid/creatinine ratio in patients with type 2 diabetes

Objectives: 1. Determination of serum uric acid concentration and serum uric acid/creatinine ratio in patients with type 2 diabetes. 2. Find out correlations between serum uric acid, serum uric acid/creatinine ratio and some clinical and paraclinical characteristics in patients with type 2 diabetes. Materials and methods: 141 patients with type 2 diabetes, at the Examination Department of Khanh Hoa Provincial General Hospital from April 2022 to June 2023; method: cross-sectional descriptive study, data processing using SPSS 18.0 software. Results: men account for 56%, women account for 44%. The average age was 55.3 ± 9.7 year. The average time to detect diabetes is 9.4 ± 6.6 year. The rate of hypertension is 42.6%. The obesity rate is 26.2%. Average waist circumference: 81.06 ± 8.9 cm. Good fasting blood glucose control accounts for 39.0%, good HbA1c control accounts for 36.9%. The average GFR is: 83.42 ± 22.81 (ml/min/1.73m2), GFR reduction accounts for 11.3%, CKD accounts for 43.9%. The average serum UA concentration was: 345.87 ± 98.57 mmol/l, the average serum UA/Cre value was: 4.23 ± 1.3, with 23.4% increased serum UA. There is a negative correlation between UA and GFR, r = - 0.409. UA concentration in the group with CKD was higher than the group without CKD, p &lt; 0.05. There is an association between UA according to CKD stage, p &lt; 0.001. There is a relationship between UA/Cre according to CKD stage, p &lt; 0.0001. There is a statistically significant relationship (p &lt; 0.001) between UA concentration and urinary ACR level. Multivariable linear regression equation: GFR = 118.122 + 5.449*UA/Cre – 0.674*Age - 3.563*Urea - 0.014*ACR, with R2 = 64.1%, B = 5.449, p &lt; 0.001. ROC curve analysis: Serum UA value: AUC = 0.767, p &lt; 0.001, PI: 433.5, Se: 56.3%, Sp: 87.2%). Serum UA/Cre value: AUC = 0.131, p &lt; 0.05. Conclusions: Serum UA/Cre ratio has prognostic value for CKD in patients with type 2 diabetes (R2 = 64.1%, B = 5.449). Serum UA concentration is valuable in predicting the occurrence of CKD in patients with type 2 diabetes (AUC = 0.767, cut-off point is 434 (µmol/l), with Se: 56.3% and Sp: 87.2%. Key words: diabetes, serum uric acid, serum uric acid/ creatinine ratio.

Study protocol for a prediction model for mild cognitive impairment in older adults with diabetes mellitus and construction of a nurse-led screening system: a prospective observational study

IntroductionWith an increasing number of older adults in China, the number of people with cognitive impairment is also increasing. To decrease the risk of dementia, it is necessary to timely...

The Impact of the Employee’s Personal Characteristics on the Abuse of Sickness Absence: Empirical Evidence From Poland

Abstract Objective The tendency to abuse sickness absence is a complex problem conditioned by many factors, that can be divided, depending on the level of impact, into three groups: micro (related to personal characteristics), meso (related to the work environment), and macro (related to the broader environment). The subject of interest in the article is the first level (micro). The aim is to evaluate the impact of various personal factors on the declared abuse of sickness leave in Poland. Research Design &amp; Methods The data was gathered using the CAWI survey. The research sample consisted of 1067 respondents (full-time employees). Statistical analysis incorporated multivariable linear regression and structural equation modelling. Findings Some personal characteristics have a significant impact on the declared abuse of sick leave. These factors are: gender, age, number of children, place of living, marital status, and subjective health. We found no impact of education and financial status. Implications &amp; Recommendations Although abusing sick leave is a serious economic and organisational problem, its causes still remain relatively poorly recognised. Personal characteristics determine the propensity to abuse sick leave, and they need to be taken into account under the process of managing absence behaviours. Contribution &amp; Value Added The added value of the study is drawing attention to the new personal factors which were not previously identified as a determinant of abuse of sick leave. These are: the number of children, place of living, and marital status.

The Sailing Boat Price Study Based on Principal Component Regression Analysis

This paper conducts research on the pricing of second-hand sailboats under certain assumptions. Initially, a substantial amount of potentially relevant indicators and data related to sailboat pricing were collected from the internet. The Pearson correlation coefficient was used to investigate the correlation between these indicators and to filter them. Due to the distinctive characteristics of sailboats, they were categorized into monohull sailboats and catamarans for separate analysis. Subsequently, the processed data were used for price prediction using a BP neural network, yielding preliminary results. To obtain an explicit method for calculating sailboat prices, this paper employed principal component analysis to calculate the pricing objective function for both types of sailboats. This led to the derivation of two multivariate linear regression equations, which were subjected to significance testing. The results indicate that the objective functions obtained in this paper can serve as references for pricing second-hand sailboats.

Effects of Aquatic Plant Coverage on Diversity and Resource Use Efficiency of Phytoplankton in Urban Wetlands: A Case Study in Jinan, China.

With the acceleration of urbanization, biodiversity and ecosystem functions of urban wetlands are facing serious challenges. The loss of aquatic plants in urban wetlands is becoming more frequent and intense due to human activities; nevertheless, the effects of aquatic plants on wetland ecosystems have received less attention. Therefore, we conducted field investigations across 10 urban wetlands in Jinan, Shandong Province, as a case in North China to examine the relationships between aquatic plant coverage and phytoplankton diversity, as well as resource use efficiency (RUE) in urban wetlands. Multivariate regression and partial least squares structural equation modeling (PLS-SEM) were used to analyze the water quality, phytoplankton diversity, and RUE. The results demonstrate that the increase in aquatic plant coverage significantly reduced the concentration of total nitrogen and suspended solids' concentrations and significantly increased the phytoplankton diversity (e.g., species richness and functional diversity). The aquatic plant coverage significantly affected the composition of phytoplankton functional groups; for example, functional groups that had adapted to still-water and low-light conditions became dominant. Furthermore, the increase in phytoplankton diversity improved phytoplankton RUE, highlighting the importance of aquatic plants in maintaining wetland ecosystem functions. This study may provide a scientific basis for the management strategy of aquatic plants in urban wetlands, emphasizing the key role of appropriate aquatic plant cover in maintaining the ecological stability and ecosystem service functions of wetlands.

Correlation of ultrasound measurement of limb muscle thickness and echo intensity with frailty assessment in elderly patients undergoing malignancies surgery

IntroductionIt remains controversial which frailty score correlates with adverse outcomes. Instead of these subjective and time consuming scores, we studied whether ultrasound guided lower extremity thickness measurements more closely are associated with adverse outcomes. MethodPatients undergoing gastrointestinal malignancy surgery were included as study subjects. Frailty was identified using the FRAIL scale assessment. Ultrasound measured the muscle thickness and echo intensity of the patient's upper and lower limbs. ANOVA was used to analyze the relationship between muscle data and frailty assessment. Significant indicators from the one-way analysis were included in the multivariate logistic regression equation. ResultsA total of 160 study subjects were included, 52 in the normal group, 78 in the prefrailty group, and 30 in the frailty group. The ANOVA showed that there were significant differences in age, hemoglobin, albumin, history of hypertension, history of coronary artery disease, the history of cerebrovascular disease, rate of postoperative complications, rate of transferring to intensive care unit, time out of bed, length of hospitalization, thickness and echo intensity of quadriceps femoris the vastus lateralis and the tibialis anterior, echo intensity of the medial gastrocnemius among the three groups (P < 0.05). Pearson's correlation analysis showed FRAIL score was correlated with muscle thickness and echo intensity of the lower limbs. Multifactor logistic regression analysis showed that the prefrailty group was positively correlated with age（β = 0.146, P = 0.004）, echo intensity of the medial gastrocnemius (β = 0.055, P = 0.031), and rate of postoperative complications（β = 1.439, P = 0.021）, also negatively correlated with muscle thickness of the tibialis anterior（β = −2.124, P = 0.007）. The frailty group was positively correlated with age（β = 0.22, P = 0.005）, tibialis anterior echo intensity (β = 0.082, P = 0.015), medial gastrocnemius echo intensity (β = 0.089, P = 0.026), cerebrovascular disease history (β = 2.311, P = 0.04), and postoperative complication rate (β = 2.684, P = 0.003). It was negatively correlated with albumin (β = −0.26, P = 0.017), quadriceps muscle thickness (β = −2.257, P = 0.017), and tibialis anterior muscle thickness (β = −5.408, P = 0.001). ConclusionUltrasound measurement of lower (not upper) extremity muscle thickness and echo intensity was significantly associated with discriminating severity of frailty and postoperative outcomes than frailty scores in elderly patients.

Employees’ professional situation and the abuse of sick leave absence in Poland

The propensity to abuse sickness leave is a complex issue conditioned by various individual and contextual factors. The aim of the article is to assess the effect of various work-related factors on the abuse of sick leave in Poland. Three categories of sick leave abuse were distinguished: compulsion, escape and recreation. The data were gathered using the CAWI survey. Statistical analyzes incorporated multivariable linear regression and structural equation modelling. The research sample consisted of 1067 respondents (full-time employees). Some work-related factors have a significant impact on the abuse of sick leave. These factors are: (1) motivational working conditions, (2) social working conditions, (3) qualifications and (4) form of ownership. The main conclusion is that the assessment of specific aspects of working conditions has a different impact on the declared abuse of sickness absence. A high assessment of the 'social’ (interpersonal) aspect is associated with a low tendency to engage in unethical behavior, whereas a high assessment of the 'motivational’ aspect is associated with a high tendency in this respect. Moreover, it was found that a low tendency to abuse is also expressed by people who highly assess their professional qualifications. Finally, abuses are committed relatively often by public administration employees.

Multivariate nonlinear regression analysis of hydraulic fracturing parameters based on hybrid FEM–DEM

PurposeThis paper aims to employ a multivariate nonlinear regression analysis to establish a predictive model for the final fracture area, while accounting for the impact of individual parameters.Design/methodology/approachThis analysis is based on the numerical simulation data obtained, using the hybrid finite element–discrete element (FE–DE) method. The forecasting model was compared with the numerical results and the accuracy of the model was evaluated by the root mean square (RMS) and the RMS error, the mean absolute error and the mean absolute percentage error.FindingsThe multivariate nonlinear regression model can accurately predict the nonlinear relationships between injection rate, leakoff coefficient, elastic modulus, permeability, Poisson’s ratio, pore pressure and final fracture area. The regression equations obtained from the Newton iteration of the least squares method are strong in terms of the fit to the six sensitive parameters, and the model follow essentially the same trend with the numerical simulation data, with no systematic divergence detected. Least absolutely deviation has a significantly weaker performance than the least squares method. The percentage contribution of sensitive parameters to the final fracture area is available from the simulation results and forecast model. Injection rate, leakoff coefficient, permeability, elastic modulus, pore pressure and Poisson’s ratio contribute 43.4%, −19.4%, 24.8%, −19.2%, −21.3% and 10.1% to the final fracture area, respectively, as they increased gradually. In summary, (1) the fluid injection rate has the greatest influence on the final fracture area. (2)The multivariate nonlinear regression equation was optimally obtained after 59 iterations of the least squares-based Newton method and 27 derivative evaluations, with a decidability coefficient R2 = 0.711 representing the model reliability and the regression equations fit the four parameters of leakoff coefficient, permeability, elastic modulus and pore pressure very satisfactorily. The models follow essentially the identical trend with the numerical simulation data and there is no systematic divergence. The least absolute deviation has a significantly weaker fit than the least squares method. (3)The nonlinear forecasting model of physical parameters of hydraulic fracturing established in this paper can be applied as a standard for optimizing the fracturing strategy and predicting the fracturing efficiency in situ field and numerical simulation. Its effectiveness can be trained and optimized by experimental and simulation data, and taking into account more basic data and establishing regression equations, containing more fracturing parameters will be the further research interests.Originality/valueThe nonlinear forecasting model of physical parameters of hydraulic fracturing established in this paper can be applied as a standard for optimizing the fracturing strategy and predicting the fracturing efficiency in situ field and numerical simulation. Its effectiveness can be trained and optimized by experimental and simulation data, and taking into account more basic data and establishing regression equations, containing more fracturing parameters will be the further research interests.

Direct and Indirect Linkages Between Trace Element Status and Health Indicators - a Multi-tissue Case-Study of Two Deer Species in Denmark.

Measuring trace element concentrations in tissue can be a valuable approach to monitor animal health status. Temporal variation in the absorption, transport, and storage of elements between different tissues can, however, complicate the assessment of element-health relationships. Here, we measured concentrations of selected essential (copper (Cu), zinc (Zn), selenium (Se)) and non-essential (arsenic (As), cadmium (Cd), lead (Pb)) trace elements within blood, liver, kidney, and hair of fallow deer (Dama dama; N=20) and red deer (Cervus elaphus; N=21). Using multivariate regression and structural equation models, we estimated direct and indirect linkages between tissue-specific trace element profiles and long- (body condition) and short-term (serum protein biomarkers for acute inflammation, infection, and malnutrition) health indicators. Trace element concentrations varied markedly and were weakly correlated among tissues, with the exception of Se. After accounting for sex- and site-differences in trace element concentrations, body condition of red deer was directly, and positively, associated to trace element status in liver and hair, but not in kidney. For both deer species, trace element status in blood was directly linked to serum protein status with an indirect positive association to deer body condition. For fallow deer, no direct association between trace element status and body condition was detected in any of the tissues, possibly because of elemental homeostasis, and because all individuals were in good clinical health. This study shows that hair can serve as an effective, non-invasive, biomarker in deer health assessments, yet, to fully uncover trace element-health relationships a variety of sample matrices is preferred.

Breast Augmentation in Transwomen: Can We have a Formula?

Background Breast augmentation in transwomen is a surgical challenge as there is no available guideline for preoperative assessment of breast implant size, which caters to them specifically. The aim of our study is to derive a formula for preoperative breast implant size estimation, which would remove the personal bias, help in one-to-one discussion, and better understanding, reducing operative time, cost, and revision surgery rate. Methods This is a retrospective study conducted from October 2018 to December 2020. We maintained a routine protocol for measurements in our patients, which has been previously published. Linear multivariate regression equation was applied to derive a formula using minimum of parameters, namely, CC (chest circumference at the inframammary fold [IMF]), POMP (circumference at the point of maximum projection of breast mound), and LOWERDIFF (lower value of difference in each breast between the stretched nipple [IMF] and the nonstretched nipple [IMF distance]). Results A total of 51 transwomen underwent surgery in this period. The mean volume of implant used was 354.51 mL. Complications consisted of pain and discomfort in six patients, delayed healing in two patients, and wound dehiscence in one. A formula for preoperative calculation of breast implant was obtained with these data. A mathematical correlation was found between complications encountered and the percentage by which the inserted implants exceeded the calculated size. Conclusion We could estimate the breast implant size preoperatively through a simple formula that require only four anthropometric measurements. This equation is a significant advantage for the surgeon and a useful tool for patient education. Its usefulness will be established if applied in prospective studies. From our study, it appears 9% above the calculated size is better avoided.